Motor control



Sept. 13, 1949. w, 5 EDDlsON 2,481,989

MOTOR CONTROL Filed Nov. 1, 1946 Tiql.

INVENTOR William Barfon Fddwon A ORNEYS Fatented Sept. 13, 1949 2,481,989 Moron CONTROL William Barton Eddison,

Irvington, N. Y., assignor to Bnrnham Corporation, a corporation of New York Application November 1, 1948, Serial No. 707,147

3 Claims.

This invention relates to motor controls and more particularly to the mounting of motors adapted to operate closures where the closures may be damaged by undue pressure thereon.

My invention is particularly adapted to the control of motors used to open and close greenhouse ventilators. This action may be automatically controlled by proper thermostatic means. However, there is a great breakage of ventilators due to obstructions such as ice forming on the ventilators and thus tending to prevent their closing. As the motors are so controlled that they will force the closing, damage is done to the ventilators and to the structure generally due to the excessive strain placed on the mechanism.

An object of this invention, therefore, is to provide a control which will prevent undue strain due to the causes mentioned but which at the same time will exert suiiicient pressure to close the ventilators when the obstruction moves.

In the case of greenhouse ventilators where ice forms on the sash, my invention will exert sufilcient pressure on the ventilators to cause them to close when the ice melts but will not exert undue pressure to damage the ventilators due to the presence of ice.

Referring more particularly to the drawings- Fig. 1 is a side elevation of an installation embodying my invention.

Fig. 2 is a plan view thereof.

Fig. 3 is a view similar to Fig. 1 showing the manner in which my invention operates.

Fig. 4 is a cross-sectional view taken on the line 4-4 of Fig. 1.

Fig. 5 is a view of the mercury switch in normal operation.

Fig. 6 shows position of the mercury switch in an emergency operation.

While I have shown a particular arrangement of motor, gear, box, springs and the mounting therefor, this arrangement is shown purely for the purposes of illustration and it is to be understood that my invention is not limited to this particular arrangement.

Referring more particularly to the drawings, I provide a mounting it which can be of any desired construction such as the posts shown, upon which is a frame ll having upwardly extending arms l2 and i4 and a yoke l5. Mounted in the yoke It is a shaft It to which is keyed the gear l1 and the arm l8. As shown in Fig. l the movement of the arm It will through the connecting arm I! open and close the ventilator 20 in the greenhouse roof 2i. In the structure illustrated the reduction gear box is mounted on a plate 26 which in turn mounts the motor 21. Lugs 28 are engaged by the springs 29 and 30 which in turn are fastened to the arms l2 and It to suspend the entire assembly consisting of a gear box 25, the plate 26 and the motor 21 on the mounting l0. Fastened to the plate 26 is a yoke which is pivoted at 38 on the shaft It. The yoke 35 carries the worm 31 on the shaft 38 extending from the gear box and engaging the gear II. In a normal operation the motor is controlled by a reversing switch 40 and a manual switch 4| to open and close the ventilator 20 through the gear box 25 and the worm 31 driving the gear I6. Mounted on the motor 21 is a mercury switch 4! connecting the lead 46 and 41 to the motor.

Should ice form on the ventilator 20 or on the roof 2i so that the ventilator cannot open or close completely, the motor will continue to operate for a period normally sufiicient to close the ventilator. Since the motor is freely mounted it will tend to assume the position shown in Fig. 3, riding up on the pivot i6 and extending the springs 30. This will cause the mercury switch 45 to assume a position similar to that shown in Fig. 6 and break the circuit. The motor will remain in that position until the ice melts or the other obstruction is removed when it can complete the closing. The action of the spring 30 is sufficient to accomplish this purpose. By the same token if for any reason the ventilator cannot be opened due to an unusual weight of snow or to the sticking of the ventilator the motor will exert pressure on the springs 29 and tilt on the pivot shaft it until the contacts of the lead 48 and 41 are exposed by the mercury switch and the circuit is broken. Should the difficulty be overcome the assembly will then be brought back to normal operating position and the circuit closed, thus preventing undue strain on the ventilators and connecting apparatus.

I claim:

-1. A motor mounting including a fixed support, a shaft in said support, a base pivoted on said shaft, a motor on said base, and spring means on said fixed support yieldingly positioning said motor in a level position.

2. A motor mounting including a fixed support, a shaft in said support, a base pivoted on said shaft, a motor on said base, and spring means on said fixed support yieldingly positioning said motor in a level position, a source of current for said motor and a circuit breaker to interrupt said source 01 current it said motor is moved out of a level position.

3. A motor mounting including a fixed support having a yoke at its upper end and a pair of horizontally extending arms, a shaft in said yoke, a base pivoted on sai shaft, 8. motor On said base, and spring members supported by said upwardly extended arms yieldingly positioning the motor in a level position, a circuit supplying current to said motor and a circuit breaker to interrupt said circuit if said motor is moved out of a leve position by undue strain.

WILHAM BARTON EDDISON.

REFERENCES CITED The following references are 01' record in the me of this patent:

Number 

